local limits calculations – methodologies for development

Local Limits Calculations – Methodologies for Development

February 24, 2002

Presented by

Rich von Langen and John W. Hart

California Water Environment AssociationP3S Annual Conference

February 24, 2004 2

Presentation Overview

Summarizes local limits development highlighting the standard approach and including practical considerations based on EPA guidance documents and experience.

February 24, 2004 3

Local Limits Development Requirements

• Management support

• Stakeholder involvement

• Adequate resources

• Work Plan

• RWQCB involvement

• Continuous process

February 24, 2004 4

Local Limits DevelopmentStandard Approach

• Determine POC

• Collect data

• Analyze data

• MAHL and MAIHL calculations

• Allocation IU local limits

• Local Limits adoption and approval

February 24, 2004 5

Pollutants of ConcernStandard Approach

• 15 Pollutants

• Pollutants in discharge permits

• Sludge disposal regulations

• Review of IU discharge data

• Identified pass-through or interference pollutants

February 24, 2004 6

Pollutants of ConcernPractical Considerations

• EPA specific evaluation criteria• Does IU discharge the POC? • Pretreatment Program versus

Source Control Program• Keep It Simple Sam (KISS)

February 24, 2004 7

Data CollectionStandard Approach

• Sampling – Flow proportional composite– Time composite– Grab

• Sample Analyses and Quality Assurance

• Flow Information

February 24, 2004 8

Sample Locations

• Domestic• Commercial• Industrial Users• Plant Process and

Removal • Waste Haulers• Source Water

February 24, 2004 9

Sample LocationsPractical Considerations

• Domestic– Representative– Sufficient flow– Over a weekend

• Commercial– Same considerations as above

February 24, 2004 10

Sample LocationsPractical Considerations (continued)

Industrial Users• Research before you

sample• Categorical Industrial

Users

• Significant Industrial Users

February 24, 2004 11

Sample LocationsPractical Considerations (continued)

Treatment Plant(s)• More than one • Hydraulic detention

time • Proper sample

locations • Sludge sample

collection

February 24, 2004 12

Sample LocationsPractical Considerations (continued)

Waste Haulers– Significant

loading?– Sample collection

technique– Different set of

local limits?

February 24, 2004 13

Sample LocationsPractical Considerations (continued)

Source Water– Different sources – Changes over time

February 24, 2004 14

Sample Analyses and Quality Assurance

• Standard or Approved Methods

• Minimum Detection Limits–What is needed?–What can be done?– Pre-qualify the laboratories

• Quality Assurance

February 24, 2004 15

Sample AnalysesPractical Considerations

• New/modified test techniques

• Minimum number of samples

• Electronic data

• Duplicate samples analyzed by two laboratories

February 24, 2004 16

Flow Information

• Flow proportional sampling

• Minimum flow and monitoring equipment capabilities

• Equalization

• Inflow and infiltration impacts

• Use actual, not design flows

February 24, 2004 17

Data AnalysesPractical Considerations

• Enough data points?

• The “< MDL” Dilemma—MDL, 50%, or 0?

• Variability-- SD > 20%, NDs

• Organic Total Dissolved Solids

• Any pass-through or interference during sampling events?

February 24, 2004 18

MAHL and MAIHL Calculations

• Mass Balances– Collection System = Headworks– Headworks = Plant Effluent and Sludge

• Safety factor

• Growth factor

February 24, 2004 19

Mass BalancesPractical Considerations

Headworks data are the fulcrum point for mass balances

Industrial Waste Residential Commercial

EffluentSludge

Headworks

February 24, 2004 20

Headworks Mass Balance

IW + RES + COM = Headworks

• Effect of collection system operations

• No commercial samples

• Headworks data versus plant removal

February 24, 2004 21

MAHL and MAIHL Practical Considerations

• If the mass balance does not balance– Eliminate data > 2SD – Use median versus mean – Balance with ND’s = MDL, X%, and 0

• Note variability for safety factor

• Compare to other data

• Influent concentration vs % removal

February 24, 2004 22

Influent Concentration Impacts on Plant Removal

0%

10%

20%

30%

40%

50%

60%

70%

80%

0 0.05 0.1 0.15 0.2 0.25

Influent Concentration--mg/L

Per

cen

t R

emo

val

February 24, 2004 23

Safety and Growth Factors

• Safety factor– Data variability– Slug loads– Plant performance

• Growth factor– Pollutant specific– Domestic/commercial – Industrial

February 24, 2004 24

Sensitivity Analysis

• NDs Calculate LL at different ND values; adjust headworks concentration to match mass balance

• Variable Data Eliminate outliers; use median or geometric mean to calculate LL

• Growth Factor Vary; compare to domestic, commercial, and IU contributions

• Allocation Method Total IU flow, pollutant contributory IU flows

• TDS Vary concentrations of source water, and uncontrolled sources

Take a Global Perspective

February 24, 2004 25

Allocation

• Meet stakeholders objectives• Mass-based • Uniform concentration– All industrial users– Only IU discharging that POC– If LL > CIU limit, allocate excess to

others

• Consistency

February 24, 2004 26

Allocation Practical Considerations

• Are limits technically achievable?

• Can compliance be determined?

• Do limits reflect actual conditions?

February 24, 2004 27

Adoption and Approval

• Local limits draft report

• Stakeholders review

• POTW adoption

• Submit to RWQCB for approval

• Issue when new permit or all at once

• RWQCB may/may not accept LL

February 24, 2004 28

Annual Review and Re-Evaluationa

• Assess current conditions – Compare MAHLs to current headworks

loadings– Review compliance history

• Collect and analyze data• Recalculate or determine LL• Implement LL

a) Unpublished presentation by Jeff Lape, US EPA

February 24, 2004 29

Continually Improving LL

Existing Load

New POC

Sample Calculate

CompareMAHL

February 24, 2004 30

EPA Resources

• Draft Guidance Manual(www.epa.gov/reg3wapd/pretreatment/pdfs_txt/draftguidance912.pdf)

• Region 8 Draft LL Development Strategy(www.epa.gov/Region8/water/wastewater/prethome/Pret_download/

LLStrategy041103.pdf)

• Region 5 LL Guidance (1995)(www.epa.gov/R5water/npdestek/npdprtg2.htm)

• Region 3 LL Guidance Domestic> MAHL (www.epa.gov/R5water/npdestek/npdprtg3.htm)

• Procuring Analytical Services (www.epa.gov/reg3wapd/pretreatment/pdfs_txt/procur.pdf)

February 24, 2004 31

Local Limits Calculations – Methodologies for Development

QUESTIONS?

California Water Environment Association

P3S Annual Conference